Fluorescent lighting fixtures can be connected to an emergency ballast and/or power system to provide emergency power in event the primary power system fails. During a power outage, the emergency power source provides sufficient power to operate the fluorescent lamps for a period of time until the power is restored. The power system typically operates the lamps at a reduced power to allow sufficient light to provide emergency lighting. The emergency power source generally includes one or more batteries that remain charged by the electrical system. The emergency ballast includes suitable circuits to recharge the batteries when the primary power source is restored.
The emergency ballast is often mounted directly to the light fixture housing on the top or the bottom. One construction is to mount the emergency ballast in the channel of the fluorescent fixture housing under the ballast cover. This generally requires a large ballast cover to enclose the emergency ballast and the ballast that is used under normal operations. The volume of the ballast, emergency power source and the required wiring often prevents the emergency ballast system from being mounted within the light fixture assembly. To accommodate for the size, the emergency ballast is often mounted on top of the light fixture housing or next to the light fixture.
One example of an emergency ballast system is disclosed in U.S. Patent Publication No. 2006/0120073 to Pickard et al. This published application discloses an emergency ballast for power fluorescent lights where the ballast has a reduced profile without the use of a bulky wiring tail. The emergency ballast includes an external header that is associated with the internal circuitry of the ballast. A connector associated with the wiring of the lighting fixture components can be inserted into or connected the emergency ballast header.
Another example of an emergency ballast is disclosed in U.S. Pat. No. 6,339,296 to Goral which discloses a low profile fluorescent lamp fixture including an AC ballast with an end of life shut down circuit. The emergency ballast includes a timing circuit which operates when AC power is restored. The timing circuit delays the application of power to the AC ballast for a given period of time during the cessation of operation of the emergency power system.
U.S. Pat. No. 6,979,097 discloses an ambient lighting system to provide light to a building. The system includes a support module, a power module, and a light fixture body. An interchangeable power module fits into the recess of the support module. The assembly can be mounted to a ceiling grid with the lighting fixture suspended below the assembly.
While the prior emergency systems have been suitable for the intended purpose, there is a continuing need in the industry for improved lighting fixtures and emergency power and ballast systems that overcome the disadvantages and limitations of the prior devices.